Speaking to BBC News, Major General James Everard, Assistant Chief of the General Staff, said:
We owe a huge apology to the families involved and those who will now be feeling stressful even if it doesn't affect them.
These were just tissue samples that we had failed to recover post-inquest and deal with in line with the families' wishes.
It's a failure of process, nothing more than that, but we absolutely recognise this will cause distress and we're deeply sorry."
More top news
An extreme endurance athlete from Cheltenham has become the first person in history to complete the British ultra-triathlon
A selection of images from Glastonbury Festival where the music has begun and weird and wonderful things are going on
Hundreds of people have shown their anger at the EU referendum result, demanding that our borders be kept open for migrants and refugees